This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to Patent Application Serial No. 0004044-4 filed in Sweden on Nov. 7, 2000, the entire content of which is hereby incorporated by reference.
The present invention relates to a key, which is intended to be used to widen an insert seat during mounting and dismounting of a cutting insert for chip removing machining. The key comprises a shaft as well as an expansion member arranged in the area of one end of the shaft. The expansion member comprises an expansion portion having an out-of-round cross-section, which expansion portion is fixed in the shaft. The shaft has a handle which, as seen in the longitudinal direction of the shaft, is spaced from the expansion member.
A key of the kind defined above is previously known from each of GB-PS-1 379 637 and WO 95/13892, said key having a shaft and an oval expansion part at a free end of the shaft. The oval expansion part is intended to be inserted in a slot of a holder for a cutting insert for chip removing machining, which slot has a smaller cross corner dimension than the maximum cross corner dimension of the oval expansion part. By turning the oval expansion part, the slot is widened, which in turn entails that the insert seat in the holder which houses the cutting insert is also widened, enabling a cutting insert to be mounted in, or dismounted from, the insert seat. If the key is rotated too far, the holder can become overloaded, which in turn may lead to fatigue of the material forming the holder.
A key of the kind defined above is previously known from, DE-PS-198 14 064, said key having a shaft and a generally triangular expansion part at a free end of the shaft. The expansion part is intended to co-operate with a semi-circular opening of a holder for a cutting insert for chip removing machining. The opening is dimensioned in such a way in relation to the triangular expansion part that when the expansion part is turned, the insert seat of the holder will be widened, which enables mounting or dismounting of a cutting insert. As in the case of the key design described above, the key is turned too far, there is a risk of overloading of the appurtenant holder, and thereby fatigue of material.
In WO 99/50012 there is disclosed a key which deals with the overloading problem by configuring the key with a polygonal cross-section, the maximum dimension of which equals a distance by which the walls of the insert seat should be separated for replacing an insert. However, that key presents a problem in that if the key is inadvertently rotated too far during a slot-widening step, the slot may close in an uncontrolled manner and/or the handle may rotate too far and injure the operator""s hand.
A primary aim of the present invention is to describe a key of the kind defined in the introduction, wherein the turning of the expansion portion is limited to an extent which ensures that the material in the holder is not overloaded. Thus, the tensile force of the parts which define a insert seat of the holder does not decline, i.e. that the material in these parts is not fatigued.
Another aim of the key according to the present invention is that a relatively small force is required for broadening the insert seat in connection with mounting or dismounting of a cutting insert.
At least the primary object is realized by a manually actuable key for widening an insert-receiving seat of an insert holder. The key comprises a shaft having a manual gripping portion, and an expansion mechanism mounted on the shaft at a location spaced from the gripping portion. The expansion mechanism comprises a mounting element carried by the shaft, with the shaft being rotatable relative to the mounting element about a rotary axis extending traversely of a longitudinal axis of the shaft. The mounting element includes a fixing section for mounting the key to the holder. The fixing section is situated farther from the manual gripping portion than is the rotary axis. The expansion mechanism further includes an expansion element connected to the shaft for rotation therewith relative to the mounting element. The expansion element extends through the mounting element parallel to the rotary axis and includes a projecting end portion projecting traversely from the mounting element and having an out-of-round cross sectional shape for insertion into the holder. A stop arrangement is provided for terminating rotation of the shaft following a predetermined extent of relative rotation between the shaft and the mounting element.
The present invention also relates to a method of widening an insert seat of an insert holder, the holder including a slot extending from an inner end of the seat. The method utilizes the above-described key and comprises the steps of:
A. mating the mounting section of the key with a corresponding mounting section of the holder and simultaneously causing the projecting portion of the expansion element to enter the slot of the holder.
B. rotating the shaft about the rotary axis relative to the mounting element and the holder, wherein the projecting portion of the expansion element rotates together with the shaft and widens the slot and the seat; and
C. performing step B until a stop surface on the shaft abuts a stop to terminate the rotation of the shaft.